This photo released Wednesday, Nov. 20, 2013 by the Saco River Auction Co., shows a tube containing a wax-covered cylinder etched with an 1893 recording of the song, Mommas Baby Black Boy, by the Unique Quartet, which is up for auction in Biddeford, Maine. It is one of two copies of the oldest known recording by a black vocal group in the U.S. (AP Photo/Saco River Auction Co.)

By DAVID SHARP

BIDDEFORD, Maine (AP) — One of two copies of the oldest known recording of a black vocal group in the U.S. is up for auction — a recording so rare and delicate that the auctioneer doesn’t dare try to play it.

The 1893 recording of “Mama’s Black Baby Boy” by the Unique Quartet pre-dates vinyl recordings. The song was recorded on a wax-covered cylinder using technology invented by Thomas Edison. It can only be played on a special cylinder player that was a predecessor to phonographs, which played flat, vinyl discs, said Troy Thibodeau, manager of Saco River Auction Co.

The 120-year-old recording, along with a second Unique Quartet song, “Who Broke the Lock (on the Henhouse Door)?” from 1896, came from a Portland collector who amassed 3,000 of the old cylinder recordings.

“They’re in fantastic shape,” Thibodeau said Wednesday, carefully showing off the smooth cylinder covered in brown wax on which the music resides in etched grooves. “All it takes is a little bit of heat or a little bit of cold, and these things are junk. So, for more than 100 years, someone really took care of these things and treasured them.”

Both cylinders are up for auction on Saturday, along with hundreds of other items, including a shirt belonging to George Custer, the cavalry captain who died in 1876 while fighting Indians at Little Bighorn in Montana.

Cylinder recordings are becoming rare, and recordings of black artists even more rare.

There are so few cylinders that have the historical significance of the Unique Quarter recordings that it’s hard to know how much they might sell for. An appraiser believes they’ll go for $25,000 or more — apiece.

The cylinders rotate on a machine that looks like an early Victrola-style player. A needle fits in the wax grooves as the cylinder spins. Such players still exist, but the wax degrades with each playing. Later phonographs featured flat platters and vinyl recordings that lasted far longer than wax.

Another black group, the Standard Quartet, is credited with making earlier cylinder recordings than the Unique Quartet, but none of those recordings exist today, said Bob Marovich, a gospel music historian in Chicago.

Marovich said he holds out hope that more of the old music could turn up. “Finding this one serves as a well of hope that maybe some more of them are out there,” he said in a telephone interview.

It’s startling how soon music can be lost.

Robert Darden, who’s working to save the music by digitizing existing vinyl recordings through the Black Music Restoration Project, estimates that 75 percent of gospel music recorded on vinyl from 1940 to 1970 has disappeared.

“All pre-digital black sacred music is at risk. The cylinders are made from pressed, hardened wax and grow brittle and chipped with age. Vinyl 78s, 45s, and LPs were melted down and recycled as part of the war effort during World War II,” said Darden, who’s a professor at Baylor University in Texas.